JPS583845B2 - Safety tire with dual puncture seal layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a safety tire with a puncture sealing layer having a two-layer structure, and more particularly, the puncture prevention layer has an adhesive layer made of an adhesive rubber composition having no three-dimensional network and a three-dimensional puncture sealing layer. It is formed from two adhesive layers made of an elastic adhesive composition with a network, and has sealing performance when a foreign object penetrates into the tire, sealing performance when the tire is running as is, and sealing performance when a foreign object is pulled out of the tire. It concerns a safety tire with significantly improved performance.

Conventionally, various safety tires equipped with a puncture prevention layer have been proposed, but the puncture prevention layer of such tires is made of an adhesive composition, and its basic ingredients are firstly a low-pressure compound that imparts adhesiveness. The second is a general-purpose rubber that gives the composition strength, and the third is an inorganic filler that gives the composition the property of fixing it to the inner surface of the tire and preventing it from moving, so-called chicken tropism. be.

A puncture seal layer made of a composition made from a combination of such components has extremely good sealing properties when foreign matter enters the tire and sealing properties when foreign matter is pulled out. The foreign object moves,
Since the tire puncture prevention layer is destroyed, albeit locally, the sealing performance has the disadvantage of rapidly decreasing.

Another drawback is that when the tire rotates at high speed, the puncture prevention layer gathers in the center of the tire.

In order to solve the above-mentioned drawbacks, a method has been considered in which a coating layer having rubber-like elasticity is further provided on the tire puncture prevention layer.

However, although this method improved the sealing performance and flow of the adhesive layer while the tire was running, the sealing performance when foreign objects were pulled out after the tire was running was significantly reduced.

Until now, no method has been developed that satisfies all of these performances.

Therefore, an object of the present invention is to solve the drawbacks of the above-mentioned safety tires equipped with a puncture sealing layer, and to provide a safety tire that has significantly improved sealing performance when a foreign object enters, when driving with a foreign object stuck in it, and when a foreign object is pulled out. It's about doing.

The present inventors conducted various studies to achieve the above object.

First of all, the most important feature of the adhesive composition that does not have a three-dimensional network, which is conventionally used in the puncture sealing layer of safety tires, is that when the composition is pinched and stretched a little, it becomes a thin filament that can be stretched forever. It is in.

This is not infinite, but is generally limited by the cohesive force and surface tension of the composition.

However, this is a property that does not occur in substances with a three-dimensional network, and if a puncture prevention layer made of this composition intrudes into a tire, when the foreign object is pulled out from the tire, the composition attached to the foreign object will be removed. It becomes a thin film or becomes a thin thread, and exhibits effective sealing performance.

However, when the tire is running, foreign objects are constantly moving, so the film made of the composition is eventually destroyed and the sealing performance is sharply reduced.

In other words, it has the disadvantage of being weak against movements at relatively high frequencies.

On the other hand, an adhesive composition having a three-dimensional network has the characteristic that when a foreign object that penetrates inside the tire moves while the tire is running, the puncture prevention layer made of the formed product can follow the movement with a relatively high frequency. .

However, a simple elastic body cannot produce sufficient effects.

The reason for this is that the elastic modulus of the foreign material is overwhelmingly higher than the elastic modulus of the rubber-like elastic material, so a large stress concentration occurs at the interface between the rubber-like elastic material and the foreign material, causing cracks in the rubber-like elastic material. We can see it growing.

To avoid this, we considered the following two methods.

(1) The modulus of the elastic body should be made as small as possible, so that stress is negligible when deformed by the movement of foreign objects.

(2) Providing a strong adhesive effect to the elastic body to prevent the creation of a space at the interface between the elastic body and foreign matter.

In order to satisfy the condition (1) above, the adhesive composition constituting the puncture seal layer must have a three-dimensional network and a
0% modulus is 1. In order to satisfy the condition (2), the adhesive composition constituting the puncture seal layer must have a three-dimensional network and the tackiness at 30°C must be 1.0 kg/cm2 or less. It was confirmed that the glass transition point must be -50°C or lower so that it can be used even at sufficiently low temperatures.

As a composition that satisfies these conditions (1) and (2) at the same time, for polyalkylene ether (A) having two or more isocyanate groups in one molecule, there are more than two isocyanate groups in one molecule. Polyalkylene ether polyol (B) having a hydroxyl group is added at a Durham equivalent ratio of 1.3 to (f2/f
1) (f1-1)+1) (where f1 is the number of isocyanate groups in the A1 molecule, f2 is the number of hydroxyl groups in the B1 molecule) per 100 parts by weight of the urethane-based compound. There is a composition having a three-dimensional network containing ~200 parts by weight.

However, when this composition that satisfies the conditions (1) and (2) above is also used as a tire puncture seal adhesive layer, foreign matter penetrates into the tire and when the foreign matter is pulled out, the adhesive does not have a three-dimensional network. It has the disadvantage of inferior sealing performance compared to other compositions.

Therefore, the present inventors considered that it would be possible to form an excellent tire puncture sealing layer that compensates for each other's shortcomings by combining the composition having the above-mentioned three-dimensional network and the composition having no three-dimensional network, and continued. Various studies were conducted.

As a result, the following findings were obtained and the present invention was achieved.

1. Compared to using an adhesive layer with a three-dimensional network and an adhesive layer without a three-dimensional network in a tire individually, using both as two layers has a better sealing effect even if the overall thickness is the same. expensive.

2. The effect is greatest when the ratio of the thicknesses of both layers is 50/50, but even if this ratio is changed significantly, no significant decrease in the effect is observed.

3. The sealing effect is great regardless of which layer is provided on the side that contacts the inner liner, but from the viewpoint of protecting the seal layer or flexing fatigue resistance, an adhesive layer that does not have a three-dimensional network is placed on the side that contacts the inner liner. A structure in which an adhesive layer with a three-dimensional network is provided thereon is more advantageous.

Therefore, the safety tire with a two-layered puncture sealing layer of the present invention has two puncture sealing layers each having different physical properties, one of which is made of general-purpose rubber made of natural rubber, synthetic rubber, or a mixture thereof. For 100 parts by weight of rubber,
Liquid adhesive 100-800 parts by weight, inorganic filler 10-3
The viscosity at 30°C is 5.00 parts by weight. O×10
Polyalkylene ether (5) consisting of an adhesive rubber composition having almost no three-dimensional network of 4 to 1,0 x 106 poise, and other layers having two or more incyanate groups in one molecule. polyalkylene ether polyol (B) having more than two hydroxyl groups in one molecule at a gram equivalent ratio of 1.3 to (f2/f1) (f
1-1) +1 (where f1 is the number of incyanate groups in the A1 molecule, f2 is the number of hydroxyl groups in the B1 molecule) 1 to 200 parts by weight of the inorganic filler per 100 parts by weight of the urethane compound The tackiness at 30℃ is 1.
．． 0kg/cm or more, 300% modulus is 1.0kg
/cm3 or less and a three-dimensional network having a glass transition point of -50°C or less.

As described above, the safety tire of the present invention has a puncture sealing layer made of a specific adhesive rubber composition without a three-dimensional network, and a puncture sealing layer made of a specific elastic adhesive rubber composition having a three-dimensional network. Although the puncture seal layer has a two-layer structure, synthetic rubbers used in the composition without the three-dimensional network include butadiene rubber, butadiene-styrene copolymer rubber, butyl rubber, halogenated butyl rubber, chloroprene rubber, acrylonitrile-butadiene rubber, etc. There are rubbers made of polymer rubbers, ethylene-propylene-diene terpolymer rubbers, etc., and mixtures thereof.

The liquid adhesive includes liquid polybutene, liquid polybutadiene, liquid polyisoprene, liquid polyisobutylene, liquid butadiene-styrene copolymer, hydrogenated rosin, hydrogenated rosin ester, and the like.

Inorganic fillers include silica, alumina, red iron oxide, magnesium oxide, calcium carbonate, asbestos, alum, carbon black, clay, titanium oxide, and mixtures thereof.

In addition to the above-mentioned components, the composition having no three-dimensional network may optionally include a commonly used anti-aging agent,
Pigments, short fibers, etc. are added.

In the composition, the viscosity at 30°C is 5.0 x 104 ~
The reason for limiting it to 1.0 x 106 poise is 5. O×104
If the poise is lower than 1.0 x 106 poise, it will easily flow when the tire rotates at high speed, and this phenomenon will occur even in normal use areas, making it industrially meaningless and undesirable. This is because the sealing performance will be poor if the temperature is too high.

Add 100 parts of the above liquid adhesive to 100 parts by weight of general-purpose rubber.
The reason for limiting the amount to ~800 parts by weight is that if it is less than 100 parts by weight, sealing performance cannot be expected, whereas if it is more than 800 parts by weight, it may flow easily when the tire rotates at high speed, or it may be relatively difficult to use general-purpose rubber. This is because the strength of the adhesive composition also decreases, resulting in poor sealing performance.

In addition, 1 part of the above inorganic filler is added to 100 parts by weight of general-purpose rubber.
The reason why the amount is limited to 0 to 300 parts by weight is that if it is less than 10 parts by weight, it will not be possible to sufficiently impart chicken tropism to the resulting composition, and if it is more than 300 parts by weight, the sealing performance will deteriorate.

Next, polyalkylene ether (A
) refers to polyethylene glycol with an incyanate group at the end, polypropylene glycol with an isocyanate group at the end, polytetramethylene glycol with an incyanate group at the end, and polypentamethylene. There are glycols in which the end of the glycol is an isocyanate group, and those in which the above components are copolymerized with other components, and they may be used alone or in a blend of two or more.

Furthermore, in the present invention, the polyalkylene ether polyol (B) having more than two hydroxyl groups in one molecule in the urethane-based formulation refers to polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polypentamethylene glycol and the above components. They are copolymerized with other components, and can be used alone or in combination of two or more.

The Durham equivalent ratio of the polyalkylene ether polyol (B) to the above polyalkylene ether (A) was 1.3.
The reason for limiting to ~(f2/f1)(f1-1)+1 is as follows.

Polyalkylene ether with terminal isocyanate group (A)
and a chemically equivalent excess amount of polyalkylene ether polyol {B
) reacts with the polyalkylene ether (A), which originally has almost no tackiness, by intentionally leaving unreacted hydroxyl groups bonded to the main chain of the polyalkylene ether polyol (B). This method takes advantage of the fact that a compound with strong adhesiveness can be produced from polyol (B).

Since the unreacted hydroxyl groups of the polyalkylene ether polyol (B) are bonded to the main chain in this way, the temperature dependence of the viscosity is much smaller than that of general softeners.

Therefore, conventional sealants that use large amounts of softeners or adhesives have a temperature of about 80°C. This composition has sufficient sealing performance even at high temperatures of 8.0°C or higher, whereas the composition loses its sealing effect at temperatures above 8.0°C.

The gram equivalent ratio of the polyalkylene ether polyol (B) to the polyalkylene ether (A) is . It will look like this:

Consider the case where theoretically the largest number of unreacted hydroxyl groups bonded to the main chain are left.

The equivalent weight of polyalkylene ether {A) is a, the number of functional groups f
1. When the number of equivalents of polyalkylene ether polyol (B) is b and the number of functional groups is f2, (A) and (B) react and bond as ~A-B-A-B~.

In order to form such a main chain, two isocyanate groups in one molecule of polyalkylene ether (A) and two hydroxyl groups in one molecule of polyalkylene ether polyol (B) should react.

In other words, the number of molecules required to form the main chain is (A),
(B) Both are a/f1.

The polyalkylene ether polyol (B
) is (a/f1)f2.

Next, after the main chain is formed, the polyalkylene ether (A)
The unreacted isocyanate group in one molecule of (f1-2
) remains, so the total is a / f 1 (f1-2
) This leaves an equivalent amount of unreacted isocyanate groups.

This unreacted isocyanate group is a/f1 (f1/2)
It should react with an equivalent amount of hydroxyl group, and the number of equivalents of polyalkylene ether polyol B required in this case is (a/f1
)(f1-2)・f2.

From the above, when the number of equivalents of polyalkylene ether (A) is a, the number of equivalents b of polyalkylene ether polyol (B) theoretically necessary to leave the largest number of unreacted hydroxyl groups bonded to the main chain is ( a/f1) ・f2+(a/f1
)(f1-2)·f2=a(f2/f1)(f1i).

However, in the present invention, as is clear from the examples, even if there is an unreacted hydroxyl group that is not bonded to the main chain, that is, a polyalkylene ether polyol (B) that does not react with the polyalkylene ether (A), the purpose can be achieved. It is possible to achieve a Durham equivalent ratio of (B)/(A) between 1.3 and (f2/fl)(fl-1)+1, preferably between 1.5 and (f2/f1)(f1- 1).

This composition requires the addition of an inorganic filler such as silica in order to improve material strength or impart chicken tropism. 1 to 200 parts by weight of an inorganic filler is added to 100 parts by weight of the system formulation.

In this case, if the amount of the compounding agent is less than 1 part by weight, the inorganic filler will not be effective, and if it is more than 200 parts by weight, the elongation and tackiness of the composition will be impaired and the sealing performance will be reduced.

As the filler, silica, carbon black, bentonite, calcium carbonate, white oxide, lead dioxide, titanium oxide, etc. are used.

Next, in the elastic adhesive composition having the three-dimensional network, when the polyalkylene ether {A) having a terminal isocyanate group and the polyalkylene ether polyol (B) react, octyl acid is added to adjust the reaction rate. Organotin catalysts such as stannous, dibutyltin laurate, dibutyltin acetate, etc. may also be present.

As described above, the safety tire of the present invention includes a puncture sealing layer made of an adhesive rubber composition having the above composition and having no three-dimensional network, and a puncture sealing layer consisting of an elastic adhesive composition having a three-dimensional network. By providing a two-layer structure on the inner surface, the synergistic effect of these two layers makes it possible to significantly improve tire puncture prevention ability compared to conventional puncture sealing layers, and its utility value is extremely large.

Next, the present invention will be explained with reference to Examples and Comparative Examples.

In the example, (1) bending resistance, (2) high-speed flow resistance,
(3) Static puncture protection, (4) Dynamic puncture protection (A
), (5) Dynamic puncture prevention (B) test was conducted by the following method.

(1) The degree of cracking after driving for 30,000 km was evaluated using an actual vehicle test.

(2) The test tire was run on an iron drum at a speed of 160 km/hour for 1 hour, and the degree of flow of the adhesive composition was evaluated.

(3) Internal pressure 1. Four types of iron nails with different dimensions, 1.8 to 3.8 mm in diameter and 32 to 90 mm in length, were inserted into the tread groove of a tire weighing 7 kg/cm2, 50 per tire. The internal pressure after driving and leaving it as it is for a day and night, and after measuring the internal pressure, it was 1.7 kg again.
After filling the internal pressure to /cm2, pull out all the nails,
After a few minutes, soap water was applied to the tread surface, and evaluation was made using two measures: the number of holes where bubbles appeared.

(4) Diameter 2. A total of six iron nails of 7 mm in diameter and 65 mm in length were driven into the groove of the tread so as to penetrate the tire, and the tire was run on an iron drum at a speed of 80 km/h until the internal pressure was 1 kg/cm2 (before running: 1.7 mm). kg/cm
) was evaluated based on the distance traveled.

(5) Diameter 2. A total of six iron nails with a diameter of 7 mm and a length of 65 mm were driven into the grooves of the tread so as to penetrate the tire, and the tires were run at a speed of 80 km/hour on a steel drum for 3000 km, and the nails were pulled out. The internal pressure was adjusted to the previous internal pressure), and the internal pressure was measured and evaluated after being left overnight.

Examples 1 to 6, Comparative Examples 1 to 2 An adhesive layer without a three-dimensional network (layer A) and an adhesive layer with a three-dimensional network (layer B) having the compositions shown in Tables 1 and 2 below. Tires provided as shown in the attached drawings (Examples 1 to 6) and, for comparison, tires provided with only an adhesive layer with or without a three-dimensional network were prepared as shown below and tested for bending resistance and high-speed flow resistance. The performance, static puncture protection, and dynamic puncture protection were evaluated.

(1) Adhesive layer without three-dimensional network.

To 100 parts by weight of general-purpose butyl rubber, 15 parts by weight of silica (Nipsil VN-3) and 1 part by weight of the above-mentioned short fibers were added, and after masticating in a kneader for 5 minutes, 1 part by weight of polybutyl rubber was added.
After adding 00 parts by weight of polybutene and mixing to make it sufficiently homogeneous, 150 parts by weight of polybutene was added and mixed with stirring until the mixture became uniform.

When attaching this adhesive layer to the inner surface of the tire, first 1.
The mixture was heated to 20°C and extruded using an extruder, and then the surface was smoothed using an electric spatula to finish.

(2) Adhesive layer with a three-dimensional network.

(Note) In the above table, PPG prepolymer: Polypropylene glycol whose terminal end is an incyanate group.

PPG: Polypropylene glycol Immediately before using the above A and B solutions, the Durham equivalent ratio of B solution to A solution is 1.66 = (f2/f1) (f1
1) was mixed, extruded onto the inner surface of the tire using an extruder, and the surface was smoothed with a spatula to finish.

The adhesives prepared as described above were applied to the inner surface of the tire in combinations as shown in Table 5 below.

The following conclusions can be drawn from the above results.

(1) Using a combination of an adhesive layer with a three-dimensional network and an adhesive layer without a three-dimensional network provides better performance than using each alone (synergistic effect)
.

(2) The best thickness ratio between the adhesive layer having a three-dimensional network and the adhesive layer not having a three-dimensional network is 1/1, but a sufficient synergistic effect can be expected even if the ratio slightly deviates from this value.

(3) The sealing effect is high no matter which one is used for the layer in contact with the inner liner, an adhesive layer with a three-dimensional network or an adhesive layer without a three-dimensional network, but from the viewpoint of bending resistance, the adhesive layer with a three-dimensional network is It is better to provide a non-stick adhesive layer on the side that contacts the inner liner.

Examples 7 to 19 Performance tests were conducted in the same manner as in Example 1 by providing an adhesive layer without a three-dimensional network (layer A) and an adhesive layer with a three-dimensional network (layer B) on the inner surface of the tire. Ta.

However, regarding the layer having a three-dimensional network, as shown in Table 6, the terminal of the polyalkylene ether is an isocyanate group, and the type of alkylene and the number of functional groups of the polyalkylene polyol are changed according to Example 1. I made it.

When the number of functional groups is not a natural number, it means that, for example, an appropriate blend of difunctional and trifunctional groups is used.

In addition, the adhesive layer having no three-dimensional network was used in Examples 1 to 3.
The same one as in 6 was used.

The same test as in Example 1 was conducted for each test tire,
The results obtained are shown in Table 7.

Examples 20 to 26 As shown in Table 6, test tires were prepared in the same manner as in Example 7 by changing the equivalent ratio of (A) and (B), and the same tests were conducted. Shown in the table.

From this result, the (B)/(A) equivalent ratio in Example 23 corresponds to (f2/fl) (fl-1), and the range of the equivalent ratio in the adhesive layer having a three-dimensional network is from 1.3 to
It can be seen that (f2/f1)(f1-1)+1.

The measured values of the glass transition temperature are as follows.

Examples 27 to 30 The structures of the adhesive layer having a three-dimensional network and the tire puncture sealing layer were the same as in Example 2, and the viscosity of the adhesive layer not having a three-dimensional network was changed to create test tires, and performance tests were conducted. , the results are shown in Table 8.

From the above results, the viscosity of the adhesive layer without a three-dimensional network is 5.5 at 30°C. O x 1 O4 ~ 1.0 x 105
I know it has to be Boyz.

[Brief explanation of the drawing]

The accompanying drawing is a sectional view of a safety tire according to an example of the present invention. 1...Tire, layer A---1.1 Puncture seal layer without a three-dimensional network, layer B---1 puncture seal layer with a three-dimensional network.

Claims (1)

[Scope of Claims] 1. A pneumatic tire having a puncture sealing layer consisting of two layers each having different physical properties on the inner surface of the tire, in which one of the puncture sealing layers is made of natural rubber, synthetic rubber, or a mixture thereof. 10 parts of liquid adhesive
0 to 800 parts by weight and 10 to 300 parts by weight of an inorganic filler, the viscosity at 30°C is 5. O×104~1. O×1
It consists of an adhesive rubber composition having almost no three-dimensional network such as 0.6 poise, and the other layer has two or more isocyanate groups in one molecule, whereas the other layer has two or more isocyanate groups in one molecule. The polyalkylene ether polyol (B) having more than 2 hydroxyl groups was prepared at a Durham equivalent ratio of 1.3(f2/f1)(f1-1)+1(
However, f1 is the number of incyanate groups in the AI molecule, f2
1 to 200 parts by weight of an inorganic filler is blended to 100 parts by weight of a urethane compound blended at a ratio of B (the number of hydroxyl groups in one molecule), and the tackiness at 30°C is 1.0 kg/cm.
As described above, the puncture seal has a two-layer structure characterized by being made of an elastic adhesive composition having a three-dimensional network having a 300% modulus of 1.0 kg/cm2 or less and a glass transition point of -50°C or less. Safety tires with layers. 2 In an elastic adhesive composition having a three-dimensional network, the Durham equivalent ratio of B to A is 1.5 to ( f2
/f1)(f1-1)
A safety tire equipped with a two-layer puncture sealing layer as described in Section 1. 3. In the elastic adhesive composition having a three-dimensional network, A is a polyalkylene ether in which the terminal of polyglopylene glycol or the terminal of polytetramethylene glycol is an isocyanate group. Safety tire with layered puncture seal layer. 4. A safety tire equipped with a two-layer puncture sealing layer according to claim 1, wherein in the elastic adhesive composition having a three-dimensional network, B is polypropylene glycol or polytetramethylene glycol. 5. A patent claim in which a layer made of an adhesive rubber composition without a three-dimensional network is arranged on the radially outer side of the tire, and a layer made of an elastic adhesive composition with a three-dimensional network is arranged on the radially inner side of the tire. A safety tire comprising a two-layered puncture seal layer according to item 1.